Reached in 8016 AT by the Neo-Edenist Vuvena sect, Sagan XXI was the twenty-first planet to be named after Carl Sagan in the Solar Dominion volume alone. A small domed habitat was set up on the small hot rocky world Vaygay, but the carbon-rich atmosphere of Sagan XXI represented a potential resource that could be used in a number of different ways.

To help them decide how best to use this resource, the Vuvena consulted their personal aivisers. Like the Edenists on their distant world in the Inner Sphere, every biont in the Vuvena sect has a symaiotic AI which helps them to process and store data and to make decisions. In the case of the Vuvena, however, these advisory entities are permanently linked together to form a transapient overmind. Any decision made by a modosophont citizen will be instantly communicated to all the other aivisers, and will affect the advice given by them to their clients.

After lengthy debate and many detailed simulations of the consequences of their various options, the Vuvena decided to build a McKendree cylinder in distant orbit around Sagan XXI, using carbon, oxygen and nitrogen lifted from the atmosphere and regolith from the planet's moon. To make a cylinder four thousand kilometers long using solar power alone would take several centuries, and would consume less than a thousandth of the planet's dense atmosphere. By 8700 the cylinder was habitable and was given the name Sagan Prime. Most of the population of this system migrated to the new habitat in the following centuries.

The Vuvena Forecasting Syndicates

The population of this large new habitat relied heavily on the advice given by their aiviser network, and the detailed predictions of the future which it could give them. Each citizen (mostly mildly tweaked humans and a few centaurs) could speculate in private about their future, and about the future of their world, and make plans accordingly; they could then consult their aiviser symaiote, which would give them an estimate of the consequences of any action they might take. Finally the citizen could make a decision, or announce eir intentions, and the aiviser would assist the citizen to achieve eir aims. At all times the aiviser network would be aware of the current decisions and declared intentions of all other citizens, and would update their prognostications accordingly.

Because the decisions and intentions of other citizens were constantly changing or being adjusted, the models maintained by the aiviser net would change constantly too, making the forecasts change also. This made decision making a difficult task, even with the advice of a transapient network, and each citizen found it necessary to continually adjust their plans and change their intentions and decisions. The excellent advice given by the network meant that the results of this complex process were almost always highly positive for all concerned, but some citizens perceived the process itself as inhibiting, tending to produce compromise solutions rather than grand projects.

As a result the first Forecasting Syndicates emerged, groups of like-minded citizens who acted together to affect the outcome of the aiviser models. If significant numbers of citizens all announced similar or complementary intentions and decisions, the forecasts produced by the aiviser net could be changed significantly. Soon there were many special-interest Syndicates, all acting to bend the projected future in ways that were favourable to their group; in many ways this situation was an improvement over the earlier situation, as the results were generally more interesting, if sometimes controversial.

The Die-Casters

Some citizens found that the constant oversight of apparently prescient transapient aivisers was uncomfortable; this discomfort increased when the aiviser net ascended to the 3rd toposophic level, creating a computroniumm-brain known as Professor Luna on the moon of Sagan XXI . These dissidents were concerned that the near-omniscience of the Professor and Er agents compromised the free-will of the citizens, so they developed Die-casting, a way of disrupting the aivisers' predictions using randomisation.

Each Die-caster possessed a set of multi-faced dice, with different options cast into the surface; by casting these dice when making certain important decisions they could reduce the predictability of those decisions, changing the anticipated future in ways that were difficult to predict. At first the aivisers worked around this, since the Die-casters would only use the dice in a limited range of situations, reducing the stochastic nature of their influence to manageable levels; but soon the Casters started to use the dice to decide when next to cast the dice, making even that choice unpredictable. A group of radical Die-Casters were expelled to Vaygay in 9783 for causing chaos with their randomisation, but the influence of this faction did not disappear completely.

Compared to the Syndicates the Die-casters remain a minority group, since the decisions made by the dice method are often sub-optimal; but a significant number of citizens use this method even today. Around 70% of the population use the Aiviser system consistently, while around 10% use randomisation at least part of the time while the rest of the population use aivisers infrequently or not at all.

The Sagan XXI Terraformation project

In 10111 several syndicates came together to announce a new project to terraform Sagan XXI; many different Syndicates came together to bend the future until the project had a respectable chance of achieving its aims. To terraform this planet quickly they decided to build a balloon/shellworld hybrid, with a habitable surface supported by a membrane suspended above the compressed bulk of the atmosphere, which has been divided into cells. This project is currently still in progress, with pulverised rock currently being hauled from the planet's surface to the habitable surface five kilometers above.